1. Field of the Invention
Embodiments of the present invention relate generally to an image forming apparatus.
2. Description of the Related Art
Image forming apparatuses employing what is referred to as an electrophotographic process are typically configured to replenish toner when an amount of toner in a developing unit which performs development becomes small. Such an image forming apparatus generally includes a toner container where supplemental toner is housed.
A main heat source that increases an ambient temperature in such an image forming apparatus is a fixing device that fixes a not-yet-fixed toner image formed on a sheet media by applying heat and pressure. The toner container is generally arranged at a position above the fixing device where an ambient temperature is likely to increase in the image forming apparatus.
Meanwhile, when the temperature of toner increases excessively high, the toner can be modified, or fused and solidified by the temperature. Examples of known techniques for cooling a toner container to reduce modification and solidification of toner in the toner container are described below. According to a technique disclosed in Japanese Laid-open Patent Application No. 2003-302892, cooling air is blown against an outer circumferential surface of a toner container. According to another technique disclosed in Japanese Laid-open Patent Application No. 2008-064901, a pipe through which cooling fluid flows is arranged near an outer circumferential surface of a toner container.
In recent years, many image forming apparatuses have achieved reduction in size and higher image forming speed, whereby ambient temperatures in the image forming apparatuses are increasing. Meanwhile, toners which can be fixed at lower temperatures are being developed to reduce power consumption and to achieve still higher image forming speeds. However, such toners are more susceptible to the influence of temperature than conventional toners.
The conventional technique disclosed in Japanese Laid-open Patent Application No. 2003-302892 that blows cooling air against the outer circumferential surface of the toner container is disadvantageous in that the blown air can stagnate at around the toner container. If images are successively formed on multiple sheets of media in this condition, the ambient temperature at around the toner container is likely to increase. Heat transferred from the ambient temperature and radiant heat from components around the toner container will likely increase the temperature of the toner container as well.
As described above, it is becoming difficult to cool a toner container of a recent image forming apparatus, in which ambient temperatures tend to be increasing, effectively enough to reduce modification and solidification of toner using the conventional technique of simply blowing air against an outer circumferential surface of the toner container. Furthermore, such difficulty will be further added by advent of toners which can be fixed at lower temperatures in the future.
Therefore, there is a need for an image forming apparatus capable of effectively cooling a toner container.